Onychomycosis - Fungal Infection of Nails, Its Patterns and Treatment

Introduction

Nail fungus is a common infection that can affect several nails at a time. It can cause discoloration and thicken the nail. Nail fungus is called onychomycosis, a widespread fungal infection affecting around 14 % of the general population.

What Is Onychomycosis?

Onychomycosis or toenail fungus occurs when fungi get between the toenail and toenail bed. It initiates as a yellow-brown or white spot below the tip of the toenail, and as the infection progresses, the nail may discolor, thicken and crumble at the edge of the toe.Onycholysis refers to the painless separation of the nail; it can be due to psoriasis, infection, or trauma to the nails. Although it is not fatal, the high incidence of the disease and slow healing can harm the work and social life of the affected individuals. Therefore, the accurate diagnosis is in effectively ruling out other possibilities.

Who Is More Prone to Fungal Nail Infections?

Anyone can get infected with a fungal infection; however, some people are more likely to get a fungal nail infection than others, such as older people (people over 60 years) and people with the following conditions -

• A nail injury or foot deformity.

• Diabetes.

• A weakened immune system, for example, in cancer or HIV (human immunodeficiency virus).

• Venous insufficiency (poor leg circulation) or peripheral arterial disease (narrowed arteries reduce blood flow to the arms or legs).

• Fungal skin infections on other parts of the body.

Moreover, in rare cases, a bacterial infection can also occur on top of a fungal infection that can lead to serious illness, which is more common in patients with diabetes and a weakened immune system.

What Are the Causes of Onychomycosis?

Various fungal microorganisms can cause nail fungus. One of the most common fungi that cause nail infections is dermatophyte. Furthermore, yeast, bacteria, and mold can also cause nail infections. The discoloration caused by the bacterial infection is usually green or black.

Even the skin fungal infection can lead to fungal infection of nails and vice-versa. In addition, a person might get a fungal infection from places such as the floor tile in a gym shower or inside dark, sweaty, moist shoes.

What Are the Types of Fungal Nail Infections?

It is crucial to understand the anatomy of a nail. It consists of proximal and lateral folds, cuticle, matrix, nail plate, nail bed, and hyponychium. The nail matrix is the growth center of the nail.

Onychomycosis may be categorized based on their clinical presentation:

1. Distal Subungual Onychomycosis:

• It is the most common form.

• An invasion of the nail bed and underside of the nail plate characterizes it.

• As the infection progresses, inflammation develops, leading to parakeratosis and hyperkeratosis.

• Parakeratosis is the abnormal and incomplete maturation of the keratinocyte (topmost skin cells), leading to its accumulation.

• Hyperkeratosis is the thickening of the outer layer of the skin.

This further leads to the following:

• Onycholysis- separation of the nail from the nail bed.

• Thickening of subungual regions.

• This area, in turn, becomes a breeding ground for bacteria and molds, giving the nail a yellowish appearance.

2. Proximal Subungual Onychomycosis:

• It is a rare type of onychomycosis.

• It occurs when the infection initiates at the proximal nail fold through the cuticle, penetrates the nail plate, and progresses distally.

3. White Superficial Onychomycosis:

• It is less common than distal subungual onychomycosis.

• It occurs when the infection occurs in superficial layers.

• It may progress to affect the lower layers.

• White or opaque patches on the surface characterize it. This emerges as the disease progresses, leading to the nails' crumbling.

• Since viable tissue is not involved, there is minimal inflammation with this type of onychomycosis.

• It is more common in toenails.

What Are the Signs and Symptoms of Onychomycosis?

Most fungal infections are not severe but can cause pain or discomfort in some patients. People with fungal toenails often have a fungal skin infection on foot. The fungal infection may cause nails to become -

• Thickened.

• Discolored.

• Brittle, crumbly, or ragged.

• Misshapen.

• Separated from the nail bed.

• Smelly.

How Is Onychomycosis Diagnosed?

The fungal nail infection can be diagnosed by a physical examination of the nail by a physician. A healthcare provider will examine the nail and can also take some nail clippings or scrape debris from under the nail, which will be sent to the laboratory for further investigations to confirm the diagnosis.

Other microorganisms can also infect nails, and knowing the cause of infection can help determine the treatment.

• Nail dystrophy (nail wasting) should be the first warning sign of nail fungus. However, other causes should be eliminated before confirming that fungi are the cause.

• Direct microscopy and fungal culture are recommended for confirmation.

• Predisposing factors such as old age, diabetes mellitus, hyperhidrosis, nail trauma, poor blood supply to extremities, and immunosuppression; help strengthen the diagnosis.

• Other features include subungual hyperkeratosis, yellow-brown discoloration, and onycholysis (separating the nail plate).

It can be challenging to differentiate onychomycosis from certain diseases with similar clinical appearances.

What Is the Treatment of Onychomycosis?

The treatment for fungal infection is not required every time and can be treated with self-care and non-prescription products. The treatment is needed when the condition gets worse or takes months to show any positive results. The treatment usually depends upon the severity of the condition and the causative organism. And even after the treatment, the condition improves, and it is common to experience recurrent infections. The treatment of fungal nail infection includes -

1. Oral Antifungal Drugs -

The doctor may prescribe oral antifungal medicines to get rid of the infection. Unfortunately, these drugs are often the first choice that has to be taken for around six to twelve weeks, and it may take even more time to eliminate the infection. In addition, these drugs can even cause serious side effects and are therefore contraindicated in patients with heart and liver problems. Moreover, patients are advised to take a routine blood test to check the progress and the effect of the drug.

Systemic antifungals have been implemented recently, including Griseofulvin, Ketoconazole, and newer antifungals such as Itraconazole, Fluconazole, and Terbinafine.

2. Topical Antifungals -

These medicines can be applied topically on the nails and are best suitable for mild to moderate infections. These can be used along with oral medications to fasten the results.

Topical agents include

• Imidazoles or azole groups: Ketoconazole, Oxiconazole, and Econazole.

• Allylamine: Terbinafine, Naftifine.

• Pyridone ciclopirox olamine.

3. Surgery -

If the above treatments do not work, the doctor may remove the entire nail and let the healthy one grow in place of the infected one.

4. Laser and Photo Dynamic Therapies -

A high-tech laser beam or special lights are used to treat fungal infections. However, these techniques are still under research, and the rate of cure is less than other treatments.

How to Prevent Onychomycosis?

Even after proper diagnosis and treatment, one in five cases shows relapse or incomplete cure.

However, this is an improvement from previous rates. The high failure rates may be due to the following:

• Inaccurate diagnosis.

• Difficulty in identifying the pathogen.

• Ruling out if secondary disorders are present such as psoriasis.

• Treatment may be complex due to the nails' thickness and excessive growth.

• High fungal inoculum.

• Drug-resistant organisms.

• Systemic disorders such as HIV, diabetes mellitus, peripheral vascular disease, or other disorders that compromise the immune system may make treatment difficult.

Some of the following habits can help prevent onychomycosis or reinfections which include -

• Keeping nails and feet clean and dry. Wash hands and feet regularly.

• Trim the nails periodically and smoothen the edges and thickened areas. Disinfect the nail trimmer after every use.

• Keep the feet dry, and remember to dry them after a bath or wearing socks or shoes.

• Wera absorbent socks and change socks regularly.

• Wear comfortable shoes that fit correctly, are neither tight nor loose, and have breathable material.

• Wear shoes in pool areas and locker rooms.

• Do not use artificial nails; choose a nail salon that thoroughly follows the sterilization procedure.

Conclusion

A fungal infection that affects the toenails is a common infection that may be difficult to treat in some cases. However, this infection does not cause pain and can be easily prevented by patient self-awareness. In the last decade, there has been significant improvement in developing safer and more efficient drugs that have helped improve the situation.In addition, maintaining dry nails and hygiene help prevent toenail infections.